Use of a sense mark to control a printing system

Abstract

A printing system includes a first imaging unit configured to print a first image and a single registration mark associated with the first image on a substrate contemporaneously during a production run, and a sensor configured to detect the registration mark at a point where the registration mark is within a second imaging unit. The printing system further includes a controller configured to calculate an offset along a width direction of the substrate based on the single registration mark and to instruct the second imaging unit to print the second image on the substrate. The second image is shifted in its entirety in accordance with the calculated offset and is printed on the same side of the substrate as the first image.

We claim: 
     
       1. A printing system, comprising:
 an apparatus to transport a web; 
 a first imaging unit configured to print on the web; 
 a controller for controlling the first imaging unit to print on the web a first image and a single registration mark associated with the first image contemporaneously during a production run; 
 a second imaging unit configured to print on the web a second image; 
 a sensor configured to detect the registration mark at a point where the registration mark is within a second imaging unit, and a sense mark; 
 the controller further configured to calculate an offset along a width direction of the web based on the position of the single registration mark on the web and to instruct the second imaging unit to print the second image on the web at a location in accordance with the calculated offset and the detection of the sense mark, wherein the second image is shifted in its entirety in accordance with the calculated offset and is printed on the same side of the web as the first image. 
 
     
     
       2. The printing system of  claim 1 , wherein the sense mark is used to register image data along a length of the web and the registration mark is used to register image data along a width of the web. 
     
     
       3. The printing system of  claim 1 , wherein the apparatus to transport the web comprises a first drum and a second drum, wherein rotation of the first and second drums transports the web past the first and second imaging units, respectively. 
     
     
       4. The printing system of  claim 1 , wherein each of the first and second imaging units includes a plurality of printheads. 
     
     
       5. The printing system of  claim 4 , further comprising a first drum associated with the first imaging unit and a second drum associated with the second imaging unit, wherein the plurality of printheads of the first imaging unit are disposed around a circumference of the first drum and the plurality of printheads of the second imaging unit are disposed around a circumference of the second drum. 
     
     
       6. The printing system of  claim 5 , wherein the web is a paper web that is driven by rotation of the first and second drums past the plurality of printheads of the first and second imaging units, respectively. 
     
     
       7. The printing system of  claim 6 , further comprising first and second sensors associated with the first and second imaging units, respectively, wherein the first and second sensors are adapted to track the speed of the first and second drums, respectively, and wherein the controller uses the speed of the first and second drums to control the first and second imaging units, respectively, to print image data on the web. 
     
     
       8. The printing system of  claim 1 , wherein the controller stores data that includes a position of the single registration mark relative to the first imaging unit and a position of the image data relative to the single registration mark. 
     
     
       9. The printing system of  claim 8 , wherein the sensor is adapted to detect a position of the registration mark and the controller controls the second imaging unit to print image data on the web in accordance with the position of the single registration mark and the stored data. 
     
     
       10. The printing system of  claim 1 , wherein the registration mark is printed along a side margin of the web. 
     
     
       11. The printing system of  claim 1 , further comprising a sense mark printer for printing the sense mark. 
     
     
       12. A printing system, comprising:
 a first imaging unit configured to print on a substrate a first image and a single registration mark associated with the first image contemporaneously during a production run; 
 a sensor configured to detect the registration mark at a point where the registration mark is within a second imaging unit; 
 a controller configured to calculate an offset along a width direction of the substrate based on the single registration mark and to instruct the second imaging unit to print a second image on the substrate, wherein the second image is shifted in its entirety in accordance with the calculated offset and is printed on the same side of the substrate as the first image, 
 wherein each of the first and second imaging units includes a plurality of printheads, 
 further comprising a first drum associated with the first imaging unit and a second drum associated with the second imaging unit, wherein the plurality of printheads of the first imaging unit are disposed around a circumference of the first drum and the plurality of printheads of the second imaging unit are disposed around a circumference of the second drum, 
 wherein the substrate is a paper web that is driven by rotation of the first and second drums past the plurality of printheads of the first and second imaging units, respectively, and 
 wherein the sensor is configured to detect the registration mark at a position after the paper web contacts the second drum and the further sensor is adapted to detect the sense mark at a position after the paper web contacts the first drum. 
 
     
     
       13. A printing system, comprising:
 means for transporting a web; 
 means for printing a first image on the web; 
 instruction means for instructing the means for printing the first image to print a first image and a single registration mark associated with the first image on the web contemporaneously during a production run; 
 means for printing a second image on the web; 
 means for detecting the registration mark at a point where the single registration mark is within a second image unit; 
 means for calculating an offset along a width direction of the web based on a position of the registration mark; 
 means for determining a location on the web where the second image is to be printed in accordance with the calculated offset, wherein the second image is shifted in its entirety and printed on the same side of the web as the first image; 
 means for instructing the means for printing the second image to print the second image on the web in accordance with the determined location; and 
 means for detecting a sense mark on the web at the first imaging unit. 
 
     
     
       14. The printing system of  claim 13 , wherein the means for detecting the registration mark comprises a sensor. 
     
     
       15. The printing system of  claim 13 , further comprising a controller that includes the calculating means and the determining means. 
     
     
       16. The printing system of  claim 13 , wherein the means for detecting the sense mark comprises a second sensor. 
     
     
       17. The printing system of  claim 16 , further comprising a third sensor adapted to detect the sense mark on the web at the second imaging unit, and wherein a controller instructs the second imaging unit to print image data on the web in accordance with the detection of the sense mark and the position of the registration mark. 
     
     
       18. The printing system of  claim 13 , wherein each of the first and second imaging units includes a plurality of printheads. 
     
     
       19. A printing system, comprising:
 an apparatus to transport a paper web; 
 a first imaging unit configured to print on the paper web; 
 a controller for controlling the first imaging unit to print a first image and a single registration mark associated with the first image contemporaneously during a production run; 
 a second imaging unit; 
 a sensor configured to detect the registration mark at a point where the registration mark is within a second imaging unit, and a sense mark; and 
 the controller further configured to calculate an offset along a width direction of the paper web based on the position of the single registration mark and to instruct the second imaging unit to print the second image on the paper web in accordance with the sense mark, wherein the second image is shifted in its entirety in accordance with the calculated offset and is printed on the same side of the paper web as the first image. 
 
     
     
       20. The printing system of  claim 19 , wherein the sense mark is used to register image data along a length of the paper web and the registration mark is used to register image data along a width of the paper web. 
     
     
       21. The printing system of  claim 19 , wherein the apparatus to transport the web comprises a first drum and a second drum, wherein rotation of the first and second drums transports the web past the first and second imaging units, respectively. 
     
     
       22. A printing system, comprising:
 means for printing a first image on a web; 
 instruction means for instructing the means for printing the first image to print a first image and a single registration mark associated with the first image on a paper web contemporaneously during a production run; 
 means for printing a second image; 
 means for detecting the registration mark at a point where the single registration mark is within a second imaging unit; 
 means for calculating an offset along a width direction of the paper web based on a position of the detected single registration mark; 
 means for determining a location on the paper web Where a second image is to be printed in accordance with the calculated offset; 
 means for instructing the second imaging unit to print the second image on the paper web in accordance with the determined position, wherein the second image is shifted in its entirety and printed on the same side of the paper web as the first image; and 
 means for detecting a sense mark on the paper web at the first imaging unit. 
 
     
     
       23. The printing system of  claim 22 , wherein the means for detecting the registration mark comprises a sensor. 
     
     
       24. The printing system of  claim 22 , wherein the means for detecting the sense mark comprises a second sensor.